Gebauer machine cannon
The Gebauer machine cannons (Hungarian: Gebauer Motorgéppuska), also known as the GKM (G'ebauer '''Kényszermeghajtású M'otorgéppuska, lit. "Gebauer positive motor-driven machine gun"), were a series of Hungarian vehicle-mounted machine guns designed by Ferenc Gebauer from 1918 to 1940, the majority of which were produced by Danuvia Ipari Es Kereskedelmi. One of the earliest attempts at a motor-driven machine gun, the Gebauer machine cannons were highly-complex machine guns mounted on various planes during World War I. History During World War I, the main armament used on aircraft was the Schwarzlose machine gun; these were converted for use on aircraft by increasing their rates of fire, with a pair of synchronized guns normally being used as the standard armament in aircraft. However, it was later discovered that the Schwarzlose guns had their faults and that something new had to be designed.http://www.hungariae.com/Gebauer.htm A designer by the name of Ferenc Gebauer later concluded that the current use of aircraft-mounted machine guns at the time was rather outdated and proposed his solution by designing a machine gun that was powered by the engine of an aircraft, rather than being synchronized with the propellers of a plane. Gebauer submitted his first design in 1918, and after some amount of experimentation, managed to produce a weapon designed to fit the purpose.http://www.airwar.ru/weapon/guns/gebauergmk.html The design was trialed a number of times, eventually proving successful and being adopted and used in a number of planes.http://www.nevpont.hu/view/10675 The last known version of the machine cannon was designed in 1940, at which point the weapons were considered underpowered compared to some 20 years ago when originally introduced, when it was regarded as modern and potent.http://www.airwar.ru/weapon/guns/gebauer1934.html Design All versions of the Gebauer machine cannon were gas-operated and were usually synchronized with the engine of a fighter plane using a crankshaft design; all versions of the machine cannon were also noted as being extremely complicated designs, with most versions of the machine cannon having an extremely high rate of fire. This crankshaft was connected to the engine of a plane; when the plane's engine is started up, this crankshaft rotates a number of gears inside the machine cannon with assistance of a crank. The bolt is connected to another crankshaft, which rotates when a locking lever is depressed when the gun fires. Versions 1918.M |justweight= |width= |height= |magazine=100-round belt |cycle=1500 rpm |minrange= |effective= |range= |alt= |usedby= |velocity= }}The first iteration of the machine cannon was the '''1918.M, designed in 1918 by Gebauer. There were three versions of the 1918.M produced, all of which were tested; design work started in 1917 when Gebauer submitted a design for an engine-driven machine gun to his commanding officer and was given approval to produce the weapon. Gebauer produced three versions of the 1918.M, all of which were tested. The first two variants of the 1918.M were regarded as poor, although the third version of the cannon was regarded as acceptable and production was allowed to begin. The guns were mounted on Aviatik D.II planes for testing. By October 1918, some 100 of these machine cannons were produced; however, the signing of the Armistice essentially prevented any sort of testing of combat effectiveness of the weapons and as such they were never used. 1926/31.M |barrel= |weight= (dual mount) |justweight= |width= |height= |magazine=500-round belt |cycle=2000 rpm |minrange= |effective= |range= |alt= |usedby=Germany Hungary Italy |velocity= }}The second iteration of the machine cannon was the 1926/31.M, designed starting in 1922 by Gebauer who was working for the Technical Experimental Weapon Division of the Honvédség at the time. The first prototype of his second weapon was known as the 22.M, which was built in prototype form only when Gebauer was still working for the Honvédség using military funding. Come 1924, Gebauer was employed by Danuvia Ipari Es Kereskedelmi; Gebauer continued to work on and perfect his designs, albeit this time funding was provided by his new employer. In 1926, Gebauer completed work on his new design, the 1926/31.M; his weapon was approved by the Honvédség shortly after. Production began the same year and ran until 1934 with 243 produced, with the guns being mounted on the FIAT CR.32 fighters, the [[wikipedia:IMAM Ro.37|Meridionali Ro.37 Lince]] and Heinkel He 46 reconnaissance aircraft and the [[wikipedia:Weiss WM-21 Sólyom|Weiss WM-21 Sólyom]] light bomber aircraft from 1926 to 1942. 1934.M |barrel= |weight= |justweight= |width= |height= |magazine=100-round Horváth detachable drum magazine (34.M, 34/40.M) 100-round belt (34/37.M) |cycle=700 – 900 rpm (34.M) 400 – 600 rpm (34/37.M) |minrange= |effective= |range= |alt= |usedby=Germany Hungary |velocity= }}The third iteration of the machine cannon was the 1934.M, designed starting in 1934. Unlike most other versions of the machine cannon, however, the 1934.M was used as a multi-purpose machine gun based on the configuration of the weapon. The initial configuration of the weapon, the 1934.M, was meant for use as an observer's gun on a mount. These were mounted and used as a secondary armament on various aircraft, with the use of a 100-round drum magazine being greater than most. The weapon was considered simpler to operate and perform maintenance on than the contemporary Schwarzlose machine gun and as such was the preferred weapon for most Hungarian soldiers on aircraft. The weapon was used by the Weiss WM-16 Budapest and WM-21 Solyóm aircraft, along with various Heinkel and Junkers aircraft used by the Germans. The 34.M was followed up with the 1934/37.M, a version of the 1934.M meant to be used on tanks. The 34/37.M was developed in 1937, some three years after the development of the 34.M. These were used on the L3/35 light tanks, 39M Csaba armored cars and 38M Toldi light tanks. Dual-mounted 34/37.Ms were also installed in tilting mounts for use on tanks,http://ftr.wot-news.com/2014/07/30/on-the-hungarian-35m-ansaldo-and-wot/ and were also used on gunboats and for anti-aircraft usage. The caliber also changed from 7.92mm Mauser to 8×56mmR. The final version of the 34.M was the 1934/40.M, designed in 1940. This version was almost identical to the 34/37.M, except that it fed from a belt instead of a drum magazine. By 1940, however, the Gebauer guns were considered underpowered due to its use of an underpowered rifle cartridge. 1939.M |weight= |justweight= |width= |height= |magazine=500-round belt |cycle=2038 rpm |minrange= |effective= |range= |alt= |usedby=Hungary |velocity= }}The fourth iteration of the machine cannon was the 1939.M, designed in 1934. The 39.M was designed as a more powerful version of the previous designs of machine cannon by Gebauer, this time being modified from the 34.M.http://www.airwar.ru/weapon/guns/gebauer1939.html Unlike all other versions of the machine cannon, the 39.M was wing-mounted.https://live.warthunder.com/post/457803/en/ Designed starting in 1936, Gebauer had perfected his design in 1939 and showed it to the staff of the Honvédség, with the rate of fire lowered to 1700 – 1800 rpm. While promising, the 39.M was ultimately not developed further as it had been proven that the 8mm cartridge the 39.M used was far too weak in defeating armor of aircraft, and that the large-caliber 40.M was being developed around the same time. While not pursued further, the 39.M ended up seeing limited use being mounted on three Heinkel He 112B fighters as the Germans were unwilling to sell the Oerlikon FFs to be mounted on the wings of the planes and as such those planes came only with MG 17 main guns. Originally, Danuvia wanted to mount their 36.M autocannons on the wings, but development of these autocannons was not completed in time for their entrance into service and as such the 39.M was used instead. 1940.M |barrel= |weight= |justweight= |width= |height= |magazine=300-round belt |cycle=2000 rpm |minrange= |effective= |range= |alt= |usedby=Hungary Italy |velocity= }}The fifth and final iteration of the machine cannon was the 1940.M, designed in 1940. The 40.M was designed as a more powerful version of the previous designs of machine cannon by Gebauer, this time being chambered for the large 12.7×81mmSR round as used by the Breda-SAFAT heavy machine gun. The 40.M was adopted by the Italians in 1940 and used on their [[wikipedia:Fiat CR.42|Fiat CR.42 Falco]] fighters, although the majority of the 40.Ms would be used on the MÁVAG Héja II fighter aircraft. These were also engine-driven and would be used until the end of the war. Come 1943, Italy obtained a license from Danuvia, allowing them to locally produce the 40.M; it is unknown how many were actually produced by the Italians under the licensing agreements. British Trials model |barrel= |weight= |justweight= |width= |height= |magazine=Belt |cycle=2000 rpm |minrange= |effective= |range= |alt= |usedby= |velocity= }}This was an experimental version of the machine cannon designed in 1933 by Gebauer and one of his colleagues, Pál Király. This was meant to be an air service gun for use in fixed or synchronized installations. This weapon was trialed by the Royal Air Force in 1934 to find a suitable weapon for use by their monoplane fighters.https://collections.royalarmouries.org/object/rac-object-277240.html Chambered in .303 British, the machine cannon was thought to be the fastest-firing single-barreled machine gun of the time, averaging at 2000 rounds per minute. While regarded as promising, the machine cannon was rejected on account of it being far too complicated and unreliable. Development on the machine cannon stopped around 1937, although it may have been a variant of the 39.M on account of their similar appearance. The prototype is now located in the Royal Armouries reference collection. Gallery Gebauer18MSurviving.jpg|An 18.M (foreground) in the Vienna Military Museum. Gebauer26MDualMount.jpg|26/31.Ms in dual mount configuration. Gebauer34MSurviving.jpg|The 34.M. Gebauer34MTiltingMount.jpg|Two 34/37.Ms in a tilting mount. Gebauer39MSurviving.jpg|The 39.M. Gebauer40MSurviving.jpg|The 40.M. References Category:Aircraft weapons Category:Autocannons Category:General purpose machine guns Category:Medium machine guns